The present invention relates to dental archwires, and, more particularly to archwires of nickel/titanium alloys which are provided with posts for engagement with orthodontic devices to provide restorative forces in orthodonture.
As is well known, highly resilient wire is employed in fabricating archwires for orthodontic applications in order to apply the desired force for the intended correction. These archwires must be secured to the orthodontic appliances affixed to the teeth, and it is generally desirable to provide posts on the wires for doing so.
Nickel/titanium alloys are considered particularly desirable for such operations because they may be preset in a configuration and a resultant "memory" as to this configuration to which the wire will attempt to return. Such nickel/titanium archwires provide a high degree of elasticity, generate a controllable force over an extended period of time, and exhibit biological inertness. However, efforts to secure posts directly to the nickel/titanium wire have not been satisfactory because the heat required to weld the posts to the wire destroys the memory and other desired properties of the wire, at least in the area where the welding is being performed.
Andreasen U.S. Pat. No. 4,037,324 describe the use of such alloys in fabricating archwires and the advantages which they afford in orthodontic appliances. Generally, such nickel/titanium alloys have a near stoichiometric composition of nickel titanium and may include small amounts of metals such as cobalt, tantalum, chromium/molybdenum to provide stiffness for some applications.
It is an object of the present invention to provide a novel archwire fabricated from nickel/titanium alloy wire on which posts are firmly secured at desired positions along the length thereof.
It is also an object to provide such an archwire in which the memory characteristics of the preset wire are used to enhance the security of the placement of the posts upon the archwire.
Another object is to provide a novel method for making such archwires utilizing easily assembled components to provide a rugged and long-lived assembly.